Patch "pwm: Fix uninitialized warnings in pwm_get()" has been added to the 3.17-stable tree

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This is a note to let you know that I've just added the patch titled

    pwm: Fix uninitialized warnings in pwm_get()

to the 3.17-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pwm-fix-uninitialized-warnings-in-pwm_get.patch
and it can be found in the queue-3.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 70145f87139fbc43b726f873813cd91dce371899 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Date: Thu, 28 Aug 2014 11:03:14 +0200
Subject: pwm: Fix uninitialized warnings in pwm_get()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

commit 70145f87139fbc43b726f873813cd91dce371899 upstream.

With some versions of gcc (e.g. 4.1.2):

drivers/pwm/core.c: In function ‘pwm_get’:
drivers/pwm/core.c:610: warning: ‘polarity’ may be used uninitialized in this function
drivers/pwm/core.c:609: warning: ‘period’ may be used uninitialized in this function

While these are false positives, we can get rid of them by refactoring
the code to store a pointer to the best match, as suggested before by
Thierry Reding. This does require moving the mutex_unlock() down.

Fixes: d717ea73e36dd565 ("pwm: Fix period and polarity in pwm_get() for non-perfect matches")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/pwm/core.c |   29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -602,12 +602,9 @@ struct pwm_device *pwm_get(struct device
 	struct pwm_device *pwm = ERR_PTR(-EPROBE_DEFER);
 	const char *dev_id = dev ? dev_name(dev) : NULL;
 	struct pwm_chip *chip = NULL;
-	unsigned int index = 0;
 	unsigned int best = 0;
-	struct pwm_lookup *p;
+	struct pwm_lookup *p, *chosen = NULL;
 	unsigned int match;
-	unsigned int period;
-	enum pwm_polarity polarity;
 
 	/* look up via DT first */
 	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
@@ -653,10 +650,7 @@ struct pwm_device *pwm_get(struct device
 		}
 
 		if (match > best) {
-			chip = pwmchip_find_by_name(p->provider);
-			index = p->index;
-			period = p->period;
-			polarity = p->polarity;
+			chosen = p;
 
 			if (match != 3)
 				best = match;
@@ -665,17 +659,22 @@ struct pwm_device *pwm_get(struct device
 		}
 	}
 
-	mutex_unlock(&pwm_lookup_lock);
+	if (!chosen)
+		goto out;
 
-	if (chip)
-		pwm = pwm_request_from_chip(chip, index, con_id ?: dev_id);
-	if (IS_ERR(pwm))
-		return pwm;
+	chip = pwmchip_find_by_name(chosen->provider);
+	if (!chip)
+		goto out;
 
-	pwm_set_period(pwm, period);
-	pwm_set_polarity(pwm, polarity);
+	pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
+	if (IS_ERR(pwm))
+		goto out;
 
+	pwm_set_period(pwm, chosen->period);
+	pwm_set_polarity(pwm, chosen->polarity);
 
+out:
+	mutex_unlock(&pwm_lookup_lock);
 	return pwm;
 }
 EXPORT_SYMBOL_GPL(pwm_get);


Patches currently in stable-queue which might be from geert+renesas@xxxxxxxxx are

queue-3.17/pwm-fix-uninitialized-warnings-in-pwm_get.patch
queue-3.17/cpufreq-avoid-crash-in-resume-on-smp-without-opp.patch
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